81732826391 has 4 divisors (see below), whose sum is σ = 82281369000. Its totient is φ = 81184283784.

The previous prime is 81732826379. The next prime is 81732826447. The reversal of 81732826391 is 19362823718.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 81732826391 - 2¹⁸ = 81732564247 is a prime.

It is a super-2 number, since 2×81732826391² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81732826361) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 274271081 + ... + 274271378.

It is an arithmetic number, because the mean of its divisors is an integer number (20570342250).

Almost surely, 2^81732826391 is an apocalyptic number.

81732826391 is a deficient number, since it is larger than the sum of its proper divisors (548542609).

81732826391 is a wasteful number, since it uses less digits than its factorization.

81732826391 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 548542608.

The product of its digits is 870912, while the sum is 50.

The spelling of 81732826391 in words is "eighty-one billion, seven hundred thirty-two million, eight hundred twenty-six thousand, three hundred ninety-one".